How To Find XOR Value Of Character Of Character Array In Java

What I am trying is find the XOR value between charcters of a String here is my code

public static void main(String[] args) {
System.out.println(grayCode("100"));
}
public static String grayCode(String input){
StringBuilder temp=new StringBuilder();
temp.append(input.charAt(0));
for(int j=1;j<input.length();j++){
char previous=input.charAt(j-1);
char current=input.charAt(j);
char xorVal=(char)(previous^current);
temp.append(xorVal);
}
return temp.toString();
}

but I am not getting actual XOR value of two charcters that I am trying to get.